On Tue, Jan 09, 2024 at 05:07:54PM +0100, Andrey Konovalov wrote:
> On Tue, Jan 9, 2024 at 4:51 PM Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> wrote:
> >
> > * Paul E. McKenney <paulmck@xxxxxxxxxx> [240109 09:04]:
> > > Hello!
> > >
> > > I get the splat shown below when running rcutorture on next-20240108
> > > (and some less-recent -next versions) on scenarios that run KASAN and
> > > that also enable CONFIG_DEBUG_LOCK_ALLOC=y. I am running gcc 8.5.0.
> > >
> > > Bisection fingers this commit:
> > >
> > > a414d4286f34 ("kasan: handle concurrent kasan_record_aux_stack calls")
> > >
> > > This commit does not appear to be trying to change the annotation
> > > required of KASAN users, so I suspect that the commit is at fault. I am
> > > including Liam in case Maple Tree is the bad guy, and should call_rcu()
> > > need adjustment, here I am. ;-)
> > >
> > > Thoughts?
> >
> >
> > I think this is ma_free_rcu() registering mt_free_rcu() in
> > lib/maple_tree.c.
> >
> > The commit you point to saves and restores the irq state in
> > __kasan_record_aux_stack(), but the trace below shows it is called prior
> > to irqs being initialized. This isn't what lockdep is yelling about, so
> > what am I missing? Maybe it will be caught after this issue is
> > resolved?
>
> Hm, I see a discrepancy in the KASAN code related to the guilty
> commit. I believed it to be harmless, but perhaps it is not.
>
> Paul, could you check if the attached patch fixes the issue for you?
> This is rather a quick fix than a proper one, but let's see if this
> one works.
>
> Thanks!
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 223af53d4338..0143c1b82004 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -208,10 +208,6 @@ static inline u8 assign_tag(struct kmem_cache *cache,
> void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
> const void *object)
> {
> - /* Initialize per-object metadata if it is present. */
> - if (kasan_requires_meta())
> - kasan_init_object_meta(cache, object);
> -
> /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
> object = set_tag(object, assign_tag(cache, object, true));
>
> @@ -338,6 +334,10 @@ void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
> if (is_kfence_address(object))
> return (void *)object;
>
> + /* Initialize per-object metadata if it is present. */
> + if (kasan_requires_meta())
> + kasan_init_object_meta(cache, object);
> +
> /*
> * Generate and assign random tag for tag-based modes.
> * Tag is ignored in set_tag() for the generic mode.
Thank you!
But no joy, please see below.
Thanx, Paul
------------------------------------------------------------------------
[ 0.131589] INFO: trying to register non-static key.
[ 0.131590] The code is fine but needs lockdep annotation, or maybe
[ 0.131591] you didn't initialize this object before use?
[ 0.131592] turning off the locking correctness validator.
[ 0.131594] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.7.0-next-20240108-00001-g1dac0fe718dd #24
[ 0.131597] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
[ 0.131599] Call Trace:
[ 0.131601] <TASK>
[ 0.131603] dump_stack_lvl+0x37/0x50
[ 0.131608] register_lock_class+0xba4/0xf30
[ 0.131612] ? x86_64_start_kernel+0xcf/0xe0
[ 0.131615] ? secondary_startup_64_no_verify+0x16d/0x17b
[ 0.131618] ? lock_release+0x1e1/0x690
[ 0.131621] ? __pfx_register_lock_class+0x10/0x10
[ 0.131624] ? lock_acquire+0x11f/0x290
[ 0.131626] ? debug_object_active_state+0x144/0x3e0
[ 0.131631] __lock_acquire.constprop.0+0x7e/0xe80
[ 0.131634] ? __pfx_lock_release+0x10/0x10
[ 0.131637] lock_acquire+0x11f/0x290
[ 0.131639] ? __kasan_record_aux_stack+0xa1/0xe0
[ 0.131644] _raw_spin_lock_irqsave+0x31/0x50
[ 0.131648] ? __kasan_record_aux_stack+0xa1/0xe0
[ 0.131651] __kasan_record_aux_stack+0xa1/0xe0
[ 0.131653] ? __pfx_mt_free_rcu+0x10/0x10
[ 0.131656] __call_rcu_common.constprop.0+0x99/0x750
[ 0.131659] ? mas_pop_node+0x12a/0x280
[ 0.131662] mas_wr_node_store+0x8c1/0x17e0
[ 0.131666] ? __pfx_register_lock_class+0x10/0x10
[ 0.131669] ? __pfx_mas_wr_node_store+0x10/0x10
[ 0.131671] ? pcpu_alloc+0x8c9/0xb10
[ 0.131676] ? find_held_lock+0x2c/0x110
[ 0.131678] ? __debug_object_init+0x2f7/0x450
[ 0.131681] ? lock_release+0x1e1/0x690
[ 0.131684] ? __pfx_lock_release+0x10/0x10
[ 0.131686] ? __pfx_do_raw_spin_lock+0x10/0x10
[ 0.131690] ? do_raw_spin_unlock+0x53/0x220
[ 0.131693] ? _raw_spin_unlock_irqrestore+0x22/0x50
[ 0.131697] mas_wr_store_entry.isra.0+0x40e/0x1480
[ 0.131700] ? __pfx___debug_object_init+0x10/0x10
[ 0.131704] mas_store_gfp+0xc2/0x1d0
[ 0.131707] ? __pfx_mas_store_gfp+0x10/0x10
[ 0.131712] ? alloc_desc+0x69b/0x990
[ 0.131715] early_irq_init+0x1c7/0x270
[ 0.131719] ? __pfx_early_irq_init+0x10/0x10
[ 0.131722] ? tracepoint_probe_register+0xaf/0xf0
[ 0.131727] ? kmem_cache_create_usercopy+0xce/0x230
[ 0.131731] start_kernel+0x162/0x390
[ 0.131734] x86_64_start_reservations+0x18/0x30
[ 0.131736] x86_64_start_kernel+0xcf/0xe0
[ 0.131738] secondary_startup_64_no_verify+0x16d/0x17b
